UniCA - a unified classification algorithm for call progress tones

To increase productivity in an outbound call center, a predictive dialer system is used to automate dialing and to route calls to available agents. Such a system needs to monitor the progress of a call so that the call is sent to an agent depending on how it completes. A call classifier is involved in detecting how a call completes. Typically a call classifier contains various DSP algorithms including ones for classifying different kinds of call progress tones (CPTs). In this paper, we propose a generic algorithm, called UniCA (unified classification algorithm) that can be used for classifying any CPT. In addition, the algorithm is efficient, deals intelligently with ambiguities and noise, and can correctly distinguish between any two theoretically distinguishable CPTs. A version of this algorithm has been implemented and is part of a commercial product. Our implementation was tested with a variety of real and simulated CPTs. The results show that our algorithm performs better than earlier algorithms.